SharePriceAssertion

Git Source

Inherits: AccessControlBaseAssertion

Title: SharePriceAssertion

Author: Phylax Systems

Applies a symmetric endpoint share-price policy to configured ERC-4626 vaults. Invariants covered:

• Endpoint share price stability: the ratio totalAssets / totalSupply must not shift more than toleranceBps between transaction start and transaction end.
• Donation policy: catches endpoint increases without proportional share minting once the vault already has nonzero supply.

Uses the V2 assetsMatchSharePriceAt precompile at transaction endpoints only. This is a simpler mixin than the full ERC4626SharePriceAssertion – it omits per-call triggers and focuses on tx-wide share price envelope protection. Use this when the access-control concern is preventing admin manipulation of share prices, rather than enforcing full ERC-4626 compliance. This is a symmetric operator policy, not an ERC-4626 invariant: legitimate yield can move the ratio upward. The executor skips comparisons when either endpoint supply is zero, so first deposit, full burn, and zero-supply donation transitions are explicitly outside its protection. Implementers must override _protectedVaults() to declare supported vaults and must calibrate tolerances from those concrete implementations.

Functions

_protectedVaults

Returns the vaults whose share prices must remain stable across the transaction.

Override to declare the protocol-specific vault addresses and tolerances. Tighter tolerances (e.g., 10 bps) are appropriate for stablecoin vaults; wider tolerances (e.g., 50-100 bps) may be needed for volatile-asset vaults or vaults with rebasing underlying assets.

function _protectedVaults() internal view virtual returns (ProtectedVault[] memory vaults);

Returns

_registerSharePriceTriggers

Register the default trigger set for share price protection.

Uses registerTxEndTrigger so the check fires once after the transaction completes. Call this inside your triggers().

function _registerSharePriceTriggers() internal view;

assertSharePrice

Verifies that all protected vault endpoint share prices are stable across the transaction.

Uses ph.assetsMatchSharePriceAt() for each vault at PreTx and PostTx. Intermediate snapshots are excluded because healthy vaults often update assets and shares at different moments inside one operation. Reverts on the first vault whose share price moved beyond tolerance.

function assertSharePrice() external view;

Errors

SharePriceChanged

error SharePriceChanged(address vault, uint256 toleranceBps);

Structs

ProtectedVault

A vault and its maximum acceptable share-price deviation.

struct ProtectedVault {
    /// @notice The ERC-4626 vault address.
    address vault;
    /// @notice Maximum allowed share price deviation in basis points. 100 = 1%.
    uint256 toleranceBps;
}